Both sentences are acceptable, and usually they will have the same practical effect. But they don't mean the same thing:
You will be sent X means that somebody will set the process in motion by directing X toward you.
You will get X means that you will end the process by receiving X.
How many times have you said “Hey, you never answered the email I sent you” and gotten back the answer “Hey, I never got it”?
So use active get when you're reasonably sure the intended recipient will in fact receive what is being sent. If you're not sure, use send—active if you want to name the sender, passive if you don’t.